The present invention relates to caps for use in combination with fluid-holding vessels, such as those designed to receive and retain biological specimens for clinical analysis and patient monitoring or diagnosis. In particular, the present invention relates to a cap which is penetrable by a fluid transfer device used to transfer fluids to or from a fluid-holding vessel, where the vessel and cap remain physically and sealably associated during a fluid transfer.
The present invention further relates to fluid transfer devices which can be used to penetrate the caps of the present invention. In particular, these fluid transfer devices are adapted to include ribs which are expected to improve the strength characteristics of the fluid transfer devices and which may aid in creating passageways for venting displaced air from within a collection device. In addition to or in lieu of these ribs, fluid transfer devices of the present invention may include grooves on their outer surfaces for creating passageways to vent air displaced from the interior of a penetrated collection device. By providing means for venting air from within a collection device, fluid transfer devices of the present invention are expected to exhibit improved volume accuracy during fluid transfers (e.g., pipetting).
Collection devices are a type of cap and vessel combination commonly used for receiving and storing biological specimens for delivery to clinical laboratories, where the specimens may be analyzed to determine the existence or state of a particular condition or the presence of a particular infectious agent. Types of biological specimens commonly collected and delivered to clinical laboratories for analysis include blood, urine, sputum, saliva, pus, mucous and cerebrospinal fluid. Since these specimen-types may contain pathogenic organisms, it is important to ensure that collection devices are constructed to be essentially leak-proof during transport from the site of collection to the site of analysis. This feature of collection devices is particularly critical in those cases where the clinical laboratory and the collection facility are remote from one another.
To prevent leakage, collection device caps are typically designed to be screwed, snapped or otherwise frictionally fitted onto the vessel component, thereby forming an essentially leak-proof seal between the cap and the vessel. In addition to preventing leakage of the specimen, an essentially leak-proof seal formed between the cap and the vessel of a collection device will also ameliorate exposure of the specimen to potentially contaminating influences from the surrounding environment. This aspect of a leak-proof seal is important for preventing the introduction of contaminants that could alter the qualitative or quantitative results of an assay.
While a leak-proof seal should prevent specimen seepage during transport, the physical removal of the cap from the vessel prior to specimen analysis presents another opportunity for contamination. When removing the cap, specimen which may have collected on the under-side of the cap during transport could come into contact with a practitioner, possibly exposing the practitioner to harmful pathogens present in the fluid sample. And if the specimen is proteinaceous or mucoid in nature, or if the transport medium contains detergents or surfactants, then a film or bubbles which may have formed around the mouth of the vessel during transport can burst when the cap is removed from the vessel, thereby disseminating specimen into the environment. It is also possible that specimen residue from one collection device, which may have transferred to the gloved hand of a practitioner, will come into contact with specimen from another collection device through routine or careless removal of the caps. Another risk is the potential for creating a contaminating aerosol when the cap and the vessel are physically separated from one another, possibly leading to false positives or exaggerated results in other specimens being simultaneously or subsequently assayed in the same general work area through cross-contamination.
Concerns with cross-contamination are especially acute when the assay being performed involves nucleic acid detection and includes an amplification procedure, such as the well known polymerase chain reaction (PCR) or a transcription based amplification system (TAS), such as transcription-mediated amplification (TMA). Since amplification is intended to enhance assay sensitivity by increasing the quantity of targeted nucleic acid sequences present in a specimen, transferring even a minute amount of pathogen-bearing specimen from another container, or target nucleic acid from a positive control sample, to an otherwise negative specimen could result in a false-positive result.
To minimize the potential for creating contaminating specimen aerosols, and to limit direct contact between specimens and humans or the environment, it is desirable to have a collection device cap which can be penetrated by a fluid transfer device (e.g., pipette tip) while the cap remains physically and sealably associated with the vessel. And, to prevent damage to the fluid transfer device which could effect its ability to predictably and reliably dispense or draw fluids, the cap design should limit the forces necessary for the fluid transfer device to penetrate the cap. Ideally, the collection device could be used in both manual and automated formats and would be suited for use with pipette tips made of a plastic material.
In addition, when a sealed collection device is penetrated, the volume of space occupied by a fluid transfer device will displace an equivalent volume of air from within the collection device. Therefore, it would be desirable to have a fluid transfer device with means for permitting air to be released from a collection device at a controlled rate as the fluid transfer device penetrates a surface of the collection device (e.g., associated cap). Without such means, a pressurized movement of air from the collection device into the surrounding environment could promote the formation and release of potentially harmful or contaminating aerosols, or bubbles in those instances where proteins or surfactants are present in the fluid sample. Therefore, a fluid transfer device which facilitates a controlled release of air from a penetrated collection device is needed to prevent or minimize the release of fluid sample in the form of aerosols or bubbles.
The present invention addresses potential contamination problems associated with conventional collection devices by providing an integrally molded cap which includes an annular flange adapted to grip an inner or outer side wall surface of a vessel at an open end of the vessel, an annular top wall which is substantially perpendicular to the annular flange, an aperture defined by the inner circumference of the annular top wall, and a conical inner wall which tapers inwardly from the aperture to an apex located substantially at the longitudinal axis of the cap. The annular flange and the conical inner wall each have substantially parallel inner and outer surfaces, and the annular top wall has substantially parallel upper and lower surfaces. (Unless indicated otherwise, the term xe2x80x9cconical,xe2x80x9d as used herein with reference to the inner wall of the cap, shall mean a generally conical shape which may be somewhat rounded as the inner wall tapers inwardly from the aperture to the apex.)
In one alternative aspect, the cap of the present invention does not include an annular flange adapted to grip a surface of the vessel. Instead, the annular top wall forms an annular ring having a lower surface which can be affixed to an upper surface of an annular rim of the vessel by such means as a fixing agent (e.g., adhesive) or, alternatively, can be integrally molded with the upper surface of the vessel.
In another alternative aspect, the cap of the present invention includes one or more ribs which extend outwardly from the inner surface of the conical inner wall. These ribs can help to form passageways between an outer surface of a fluid transfer device and the inner surface of the conical inner wall of the cap. Furthermore, these ribs will typically minimize the surface area of the cap which comes into contact with a penetrating fluid transfer device, thereby limiting frictional interference between the fluid transfer device and the cap as the fluid transfer device is being withdrawn from a penetrated cap.
The present invention addresses potential air displacement problems associated with conventional fluid transfer devices penetrating sealed collection devices by providing a fluid transfer device having a hollow body which includes one or more ribs extending outwardly from an outer surface, an inner surface, or both the inner and outer surfaces of the fluid transfer device. When the ribs are located on the outer surface, they are expected to facilitate the formation of passageways between the outer surface of the fluid transfer device and a penetrated surface material of a cap. These passageways were found to advantageously facilitate the release of air displaced from a penetrated collection device, while minimizing the formation and/or release of fluid sample in the form of an aerosol or bubbles. In some cases, the ribs are also expected to improve the strength characteristics of a fluid transfer device, so that the fluid transfer device (e.g., plastic pipette tips) is less likely to bend or buckle when contacting a penetrable surface. Improved strength characteristics are expected whether the ribs are positioned on the outer or the inner surface of the fluid transfer device.
In an alternative aspect, the fluid transfer device of the present invention includes one or more grooves recessed from an outer surface of the fluid transfer device which can likewise facilitate the formation of passageways between the outer surface of the fluid transfer device and a penetrated surface material of a cap. Also contemplated by the present invention are fluid transfer devices having both ribs and grooves.
In a first embodiment of the present invention, the conical inner wall has a single angle with respect to the longitudinal axis of the cap. The cap of this embodiment is, in a preferred aspect, penetrable by a fluid transfer device consisting of a plastic pipette tip, and the penetrable portion of the cap does not significantly impair the pipette tip""s ability to accurately draw a fluid substance after the cap has been penetrated by the pipette tip.
In a second embodiment of the present invention, the conical inner wall of the cap includes a plurality of striations which extend radially outwardly from the apex, or from one or more start-points near the apex, of the conical inner wall. Each of the striations extends partially or fully from the apex, or from a start-point near the apex, of the conical inner wall to an outer circumference of the conical inner wall. The striations may be in the form of grooves, etchings or a series of perforations on at least one surface of the conical inner wall, and the thickness of each striation is less than the thickness of non-striated portions of the conical inner wall. The striations were advantageously found to reduce the force needed to penetrate the cap and to concomitantly create air passageways between portions of the conical inner wall and the fluid transfer device as sections of conical inner wall, defined by the striations, peeled away from the fluid transfer device upon penetration.
In a third embodiment of the present invention, the inner surface of the conical inner wall includes one or more ribs which preferably have a longitudinal orientation. The ribs may be elongated structures or, for instance, protuberances or series of protuberances which aid in forming passageways for venting displaced air from a penetrated collection device. As indicated above, the ribs should, in some applications, minimize frictional contact between a fluid transfer device and a penetrated surface of a collection device as the fluid transfer device is being withdrawn from the penetrated surface.
In a fourth embodiment of the present invention, the annular flange has an upper portion which extends vertically above the annular top wall, so that the upper surface of the annular top wall can serve as a ledge for positioning and maintaining a wick material substantially above the conical inner wall and within the annular flange. The wick may be of any material or combination of materials designed to inhibit the release of bubbles, aerosols and/or to provide a wiping feature for removing fluid present on the outside of a fluid transfer device as it is being withdrawn through the cap of a collection device. The wick material preferably draws fluid away from the fluid transfer device by means of capillary action.
In a fifth embodiment of the present invention, the cap further includes a seal which is affixed to the annular top wall or an annular top surface of the upper portion of the annular flange, or is otherwise fixedly positioned within an inner surface of the annular flange (e.g., a hollow-centered resin disk with a seal affixed thereto and sized to frictionally fit within an inner surface of the annular flange and to permit passage therethrough by a fluid transfer device). While the seal is preferably penetrable with a fluid transfer device, the seal may be applied to or associated with the cap in such a way that it can be separated from the cap prior to penetration with a fluid transfer device. The seal may be provided to protect the conical inner wall (and the wick, if present) from contaminants, to limit the release of an aerosol from the collection device once an associated cap has been penetrated and/or to retain the wick within the annular flange. As indicated, the seal is preferably made of a penetrable material, such as a metallic foil or plastic, and is affixed to the cap so that it completely or partially covers the conical aperture prior to penetration.
In a sixth embodiment of the present invention, a cap is provided which can be penetrated by a plastic pipette tip by applying a force of less than about 8 pounds to a surface of the cap. The cap of this embodiment preferably includes a wick positioned above or below a penetrable surface material of the cap and requires less than about 4 pounds pressure for the pipette tip to penetrate. When included, the wick is arranged in the cap so that it can at least partially arrest the movement of an aerosol or bubbles from an associated vessel during and/or after penetration of the cap by the plastic pipette tip.
In a seventh embodiment of the present invention, an overcap containing a wick is provided which can be positioned over a cap of the present invention. An annular top wall of the overcap includes an inner circumference which defines an aperture which has been sized to receive a fluid transfer device for penetrating the conical inner wall of the cap. Ribs may be further included on an inner surface of an annular flange of the overcap to provide a frictional fit between the inner surface of the overcap and the annular outer flange of the cap. A seal may also be applied to the annular top wall of the overcap to further minimize aerosol or bubble release from a collection device once the cap has been penetrated and/or to retain the wick within the annular flange of the overcap. The overcap, which provides the benefits of aerosol and bubble containment in a separate component, may be optionally employed, for example, with a collection device having a cap lacking a wick when the sample to be removed and analyzed is suspected of containing a target nucleic acid analyte which is to be amplified before a detection step is performed.
In an eighth embodiment of the present invention, a fluid transfer device is provided which may be used to facilitate penetration of the cap or overcap of the present invention and/or which may improve venting of air displaced from an enclosed collection device as it is being entered by the fluid transfer device. This particular fluid transfer device is hollow in construction (although the fluid transfer device may be outfitted with an aerosol impeding filter), designed to be engaged by a probe or extension associated with a robotic or manually operated fluid transfer apparatus for drawing and/or dispensing fluids, and includes one or more ribs. These ribs extend outward from an outer surface of the body of the fluid transfer device and preferably have a longitudinal orientation starting from a point or points at or near the distal end of the fluid transfer device. (As used herein, the term xe2x80x9clongitudinal orientationxe2x80x9d shall mean a generally lengthwise orientation.)
In a ninth embodiment of the present invention, a plastic pipette tip is provided which has hollow tubular and conical sections for the passage of air and/or fluids therethrough and one or more lower ribs located on the conical section which extend outward from an outer surface of the conical section. These lower ribs are expected to provide the same benefits attributable to the eighth embodiment of the present invention.
In a tenth embodiment of the present invention, a plastic pipette tip is provided which has hollow tubular and conical sections for the passage of air and/or fluids therethrough and one or more lower ribs located on the conical section which extend inward from an inner surface of the conical section. As with the eighth embodiment, these lower ribs are expected to facilitate penetration of the caps and overcap of the present invention
In an eleventh embodiment of the present invention, a plastic pipette tip is provided which has hollow tubular and conical sections for the passage of air and/or fluids therethrough and one or more upper ribs on the tubular section which extend outward from an outer surface of the tubular section, with at least one of these upper ribs having a terminus at or near the distal end of the tubular section. These upper ribs are designed to aid in the formation of air gaps or passageways between the penetrated surface material of a cap and the pipette tip to facilitate the movement of air displaced from the interior of a collection device as it is being entered by the pipette tip and/or so that the air pressures inside and outside of the collection device can quickly equilibrate upon penetration of the cap.
In a twelfth embodiment of the present invention, a plastic pipette tip is provided which combines the lower and upper ribs of the ninth and eleventh or tenth and eleventh embodiments described above, where the lower ribs may be distinct from the upper ribs or pairs of lower and upper ribs may form continuous ribs extending from a point or points on the conical section to a point or points on the tubular section.
In a thirteenth embodiment of the present invention, a fluid transfer device is provided which may be used to improve venting of air displaced from an enclosed collection device as it is being penetrated by the fluid transfer device. This fluid transfer device is hollow in construction, designed to be engaged by a probe or extension associated with a robotic or manually operated fluid transfer apparatus for drawing and/or dispensing fluids, and includes one or more grooves. These grooves are recessed from an outer surface of the body of the fluid transfer device and preferably have a longitudinal orientation. The grooves of this embodiment may be used alone or in combination with the ribs of any one of the eighth, ninth, tenth, eleventh and twelfth embodiments described above.
In a fourteenth embodiment of the present invention, a method is provided for displacing air from a collection device having an enclosed chamber. In this method, a surface of the collection device is penetrated with a fluid transfer device and air is released from the collection device through a passageway formed between the surface of the collection device and an outer surface of the fluid transfer device. The fluid transfer device used in this method could be the fluid transfer device of the thirteenth embodiment described above.
In a fifteenth embodiment of the present invention, another method is provided for displacing air from a collection device having an enclosed chamber. In this method, a surface of the collection device is penetrated with a fluid transfer device and air is released from the collection device through a passageway formed adjacent to a point of contact between the surface of the collection device and a rib positioned on an outer surface of the fluid transfer device. The fluid transfer device used in this method could be the fluid transfer device of any one of the eighth, ninth, twelfth and thirteenth embodiments described above.
In a sixteenth embodiment of the present invention, a method is provided for removing a fluid substance from a collection device which includes penetrating a cap component of the collection device with a plastic fluid transfer device by applying a force of less than about 8 pounds to a surface of the cap. Once the cap has been penetrated, a fluid substance present in a vessel component of the collection device is withdrawn by the fluid transfer device before removing the fluid transfer device from the collection device.
In a seventeenth embodiment of the present invention, another method is provided for removing a fluid substance from a collection device which includes piercing a surface of the collection device after contacting the surface of the collection device or a surface of the fluid transfer device with a lubricant, such as a detergent. Subsequent to piercing the surface of the collection device, the fluid transfer device draws at least a portion of a fluid substance contained in a vessel component of the collection device before being completely removed from the collection device. The lubricant, which may be contained in a specimen-bearing transport medium held by the vessel, is expected to reduce the frictional forces between the surface of the collection device and the outer surface of the fluid transfer device as the fluid transfer device is being removed from the collection device.
In an eighteenth embodiment of the present invention, yet another method is provided for removing a fluid substance from a collection device which includes a first step for puncturing a surface of the collection device with a fluid transfer device followed by a second step for penetrating or entering the collection device so that a distal end of the fluid transfer device comes into contact with a fluid substance contained in a vessel component of the collection device. The first and second steps of this method may be performed at the same or different speeds. When the steps are performed at the same speed, a pause interrupts the movement of the fluid transfer device between the first and second steps. And when the steps are performed at different speeds, the speed of the fluid transfer device in the second step is greater than the speed of the fluid transfer device in the first step. An intervening pause may also be introduced between the first and second steps when these steps are carried out at different speeds. After contacting the fluid substance, the fluid transfer device draws at least a portion of the fluid substance before it is completely removed from the collection device. This two-step penetration method was found to improve the volume accuracy of fluid samples being withdrawn from collection devices.
In a nineteenth embodiment of the present invention, a further method is provided for removing a fluid substance from a collection device which includes penetrating a surface of a collection device with a conically-shaped pipette tip and then inserting the pipette tip into the collection device until a distal end of the pipette tip comes into contact with the fluid substance. After contacting the fluid substance, the distal end of the pipette tip is partially or fully removed from the fluid substance a sufficient distance so that one or more passageways are formed or enlarged between an outer surface of the pipette tip and the penetrated surface of the collection device. (The passageways aid in venting of air from within the collection device, facilitating greater volume accuracy during fluid aspirations.) The pipette tip then draws at least a portion of the fluid substance contained in the collection device before the pipette tip is completely removed from the collection device.
In a twentieth embodiment of the present invention, yet a further method is provided for removing a fluid substance from a collection device which includes positioning a specimen retrieval device (e.g., swab) along an inner surface of a side wall of a vessel component of the collection device by means of fixedly associating the vessel with a cap component of the collection device. The cap is then penetrated with a fluid transfer device which draws a fluid substance from the vessel before the fluid transfer device is removed from the collection device.
In a twenty-first embodiment of the present invention, a method is provided for containing an aerosol substantially inside of a collection device after a cap associated with the collection device has been penetrated by a fluid transfer device, such as a plastic pipette tip, where the cap contains a wick. Penetration of the cap results in the formation of at least one passageway which may be partially open during penetration of the cap by the fluid transfer device and/or during removal of the fluid transfer device from the collection device. The wick, therefore, may aid in containing an aerosol within the collection device (either partially or completely) as the fluid transfer device is entering an interior chamber of the collection device, as the fluid transfer device is being withdrawn from the collection device and/or after the fluid transfer device has been completely withdrawn from the collection device. The material selected for the wick, and its arrangement inside of the cap, should be such that the material will not substantially impede movement of the fluid transfer device into or out of the collection device. This method is particularly useful when the collection device contains a fluid sample suspected of having a target nucleic acid analyte which will be subsequently amplified using any known amplification procedure prior to a detection step.
Caps of the present invention may be provided in packaged combination with at least one of a vessel, a reagent (e.g., transport medium or positive control), an overcap, a fluid transfer device and a specimen retrieval device (e.g., swab or other type of probe used for specimen collection). Likewise, the overcaps of the present invention may be provided in packaged combination with at least one of a cap, a vessel, a reagent, a fluid transfer device, and a specimen retrieval device. To be in packaged combination, it is to be understood that the recited items merely need to be provided in the same container (e.g., mail or delivery container for shipping), and it is not a requirement that the items be per se physically associated with one another in the container or combined in the same wrapper.